// back to the slice being appended to, and returns nil.
// inplace MUST be set to false if the slice can be SSA'd.
// Note: this code only handles fixed-count appends. Dotdotdot appends
// have already been rewritten at this point (by walk).
func (s *state) append(n *ir.CallExpr, inplace bool) *ssa.Value {
	// If inplace is false, process as expression "append(s, e1, e2, e3)":
	//